25 December 1968: During the 10th orbit of the Moon, the crew of Apollo 8 fired the Service Propulsion System (SPS) of the Command Service Module for the Trans Earth Injection (TEI) maneuver that would send them home.
TEI was a critical maneuver which had to be timed perfectly. It occurred while the spacecraft was on the side of the Moon away from Earth, and so the crew was out of radio communication with Mission Control in Houston, Texas. If initiated too soon, the Apollo capsule would miss Earth, or ricochet off the atmosphere. Too late and the capsule would re-enter too steeply and burn up.
The engine had to burn for precisely the correct amount of time to accelerate the space craft out of lunar orbit and to arrive at Earth at exactly the correct point in space where where our home planet would be 57 hours, 26 minutes, 56.2 seconds later, as it traveled in its orbit around the Sun.
The SPS engine was an AJ10-137, built by Aerojet General Corporation of Azusa, California. It burned a hypergolic fuel combination of Aerozine 50 and nitrogen tetraoxide, producing 20,500 pounds of thrust (91.19 kilonewtons). It was designed for a 750 second burn, or 50 restarts during a flight. The SPS engine had already been used for the Trans Lunar Injection maneuver, sending Apollo 8 from Earth orbit to the moon, and now served the same function in reverse.
The SPS started at mission time T+089:19:16.6 and cut off at T+089:22:40.3, a burn duration of 3 minutes, 23.97 seconds, increasing the velocity (Δv, or “delta–v”) 3,531 feet per second (1,076 meters per second).
At Istres, in the south of France, French World War I fighter ace and test pilot Raymond Delmotte flew a Caudron C.460 Rafale single-engine monoplane over a 3-kilometer (1.864 miles) straight course at an average speed of 505.85 kilometers per hour (314.32 miles per hour), setting a new Fédération Aéronautique Internationale (FAI) world record speed for land planes.¹
Flight reported the event:
“. . . The attempt consisted of four trial flights over a regulation three-kilometre straight course, the average time made during all of them being taken as the final result. Delmotte made a preliminary attempt in the morning, but, owing to a crosswind of 10 m.p.h. then prevailing, he was able to attain only 478 km./hr. as the average result. He then waited until the afternoon, when, the wind having fallen to about 2½ m.p.h., he took off again and accomplished an average speed of 505.84 km./hr., according to the official timers, who will submit this figure to the F.A.I. for homologation.”
—FLIGHT The Aircraft Engineer & Airships, No. 1358, Vol. XXVII, Thursday, 3 January 1935 at Page 16
The New York Daily News reported that Delmotte won a prize of 300,000 francs, equivalent to $19,000 U.S. dollars.
The Caudron C.460 Rafale was designed by Marcel Riffard, technical director of Société des Avions Caudron, a French aircraft manufacturer which had been established in 1909. (Rafale means gust: “a brief, strong, rush of wind.”) It was a light-weight, single-seat, single-engine racer with retractable landing gear. Three were built.
The airplane was primarily constructed of spruce, covered with doped fabric, with the engine cowling and fuel tanks fabricated of magnesium. It was 7.125 meters (23 feet, 4½ inches) long with a wingspan of 6.75 meters (22 feet, 1¾ inches) and overall height of 1.8 meters (5 feet, 11 inches). The C.460’s empty weight was 520 kilograms (1,146 pounds) and it had a gross weight of 875 kilograms (1,929 pounds).
The C.460s were originally powered by an air-cooled, supercharged, 7.947-liter-displacement (484.928 cubic inches) Renault 6Q inverted 6-cylinder inline overhead valve (OHV) engine. It had 2 valves per cylinder and a compression ratio of 6:1. The engine produced 310 horsepower at 3,000 r.p.m., and 325 horsepower at 3,200 r.p.m. The direct-drive, left-hand tractor engine turned a two-bladed metal Helices Ratier automatic variable-pitch propeller with a diameter of 1.80 meters (5 feet, 10.9 inches). The Renault 6Q was 1.62 meters (5 feet, 3.8 inches) long, 0.93 meters (3 feet, 0.6 inches) high and 0.52 meters (1 foot, 8.5 inches) wide. It weighed 190 kilograms (419 pounds).
Prior to Delmotte’s speed record attempt, the C.460’s engine was changed to a larger, more powerful 9.501 liter (579.736 cubic inches) Renault 6Q engine, also a direct-drive engine, which produced 370 chaval vapeur (364.9 horsepower) at 3,250 r.p.m. The engine’s centrifugal supercharger turned 26,000 r.p.m. The variable-pitch Ratier propeller was retained.
There is little biographical information available about Raymond Delmotte. He was born at Saint-Quentin, Aisne, France, 11 November 1894. He married Mlle Louisa Dagneaux, and they had three children, Fernande, Raymond, and Ann Marie. He held ten FAI records for speed and distance. He died 13 December 1962.
The Rue Raymond Delmotte in Saint-Quentin is named in his honor.